This invention relates to apparatus which can be used to stun, or slaughter, small animals and fish. In particular, the invention relates to pneumatically operated apparatus.
Processing of animals for food usually involves the initial slaughter of the animal. In the processing of larger animals such as cattle, this is typically done by a blow to an animal""s head using a pneumatically- or cartridge-powered gun with a captive bolt or piston in place of a projectile.
Processing of some fishes also requires slaughter as an initial step in the process. For example, salmon are typically xe2x80x9cstunnedxe2x80x9d by a blow to the head before processing as food. In many instances, the blow is applied with a simple club, there being no readily available apparatus for the procedure. Smaller animals such as rabbits are similarly stunned by a blow to the head, there again being no readily available apparatus suitable for use with animals of this size.
Any apparatus must be capable of delivering a blow to the head of an animal or fish in such a way that stunning can be done humanely. For most processing needs, the apparatus must also be capable of delivering blows quickly and repetitively so that large numbers of animals or fish can be processed.
Pneumatically powered apparatus is used for larger animals because it meets the needs set out in the previous paragraph. However, such apparatus is not suitable for use with smaller animals or fish. Smaller hand-held pneumatic devices are knownxe2x80x94for example, pneumatically powered nail gunsxe2x80x94but these are not suitable for use as a fish or animal stunning device because of their configurations. Such devices are nevertheless capable of delivering an adequate force.
The object of the invention is to provide a stunning device that can be used for the rapid and repetitive stunning of small animals or fish and that utilizes pneumatic power.
In a broad format, the invention provides an animal or fish stunning device comprising:
a pneumatically-powered piston assembly comprising a piston retractably extendable from an open ended cylinder included in said assembly;
a support for said piston assembly including a base member, wherein said piston assembly is positioned with respect to said base member to define a space between said base member and said cylinder open end for receiving a head of an animal or fish, and wherein said piston can extend partially into said space; and
a trigger for activating extension of said piston when said trigger is contacted by the head of said animal or fish when positioned in said space.
The operating principle of the stunning device according to the invention is that that the animal or fish is killed by a blow to the head administered by the piston of the device. The action is initiated by insertion of the animal""s or fish""s head into the space between the base member of the support for the piston assembly and the open end of the cylinder whereby contact with a trigger activates the piston. The trigger and cylinder are configured such that when the piston is activated, it strikes the animal or fish just behind and/or between the eyes. This impact is sufficient to kill the animal or fish due to the shock to the brain.
A design feature of the device is that when activated, the piston extends only once and then retracts. Removal of the animal or fish resets the trigger so that the device can be immediately used to stun another animal or fish.
The piston assembly of devices according to the invention is advantageously pivotally mounted to the support so that the distance between the base member and the open end of the cylinder can be adjusted to allow use with differently sized animals and fishes. The piston assembly can be either fixed in a particular position or mounted such that some degree of movement is possible. This allows for automatic adjustment of the distance between the base member and the open end of the cylinder when differently sized individuals of the same species of animal or fish are to be slaughtered.
The mounting of the piston assembly to the support is typically such that the assembly can be demounted to allow cleaning of both components. Devices advantageously include guide plates to facilitate insertion of the head of the animal or fish into the space between the base member of the support and the open end of the cylinder. Preferably, the distance between guide plates at each side of the entrance to the device is adjustable. Advantageously, the entire device can be dismantled for cleaning of all components.
The support for the piston assembly advantageously comprises a planar base member and planar side members. Alternatively, the support can be a framework of elongate members.
The pneumatic operation of the piston is typically effected by incorporating apparatus commonly known as a xe2x80x9cnail gunxe2x80x9d in the piston assembly of devices according to the invention. As such guns are typically capable of repetitive firing on activation, devices include a mechanism which allows only a single extension of the piston. This will be explained in greater detail below. However, it will be appreciated by one of skill in the art of the manufacture of such devices that the pneumatically-operated piston can be any suitable assembly including a purpose-built assembly.
Devices according to the invention can be used with small animals and are particularly suited for use with animals having a weight of 2 to 7 kg. With regard to fishes, devices can be conveniently used with fish having a weight of up to about 7 kg such as salmon, trout and sea bass. Devices are most particularly suited for the stunning of salmon during the commercial processing thereof.
With devices according to the invention, animals or fish to be processed can be rapidly and efficiently stunned with minimal risk of injury to the operator. Furthermore, as triggering is effected by the head of the animal or fish, both hands of the operator can be used to guide the head of the animal or fish into the device. An additional advantage of devices according to the invention is that the external appearance of the animal or fish is not affected by the killing process. This is particularly important for sale of whole fish. The quality of fish is also enhanced through more rapid and humane killing at the point of harvest.
Having broadly described the invention, stunning devices will now be exemplified with reference to the drawings briefly described hereafter.